1. Field of the Invention
The subject invention provides an audio crossover system and method.
2. Description of the Prior Art
The way humans hear sounds is complex. The auditory canal within the human ear is a long tube and it possesses resonances and peaks at certain frequencies. The lowest resonance is broadly peaked around 3 kHz and appreciable gains are incident from about 2 kHz to 6 kHz.
This frequency range that is accentuated by human hearing coincides with the frequency range in which important lingual sounds have their major spectral contents. Sounds like “p” and “t” have very important parts of their spectral energy within the “accentuated” range, making them easier to discriminate between. To hear sounds in the accentuated range is vital for speech communication.
When exposed to an incident directional sound field and including diffractive effects of the head, the maximum sound pressure level (SPL) at the eardrum can be approximately 7 dB to 20 dB higher than in the incident field, depending on the direction of the sound. In effect this gives humans a sensitivity increase within the range from around 2 kHz to 6 kHz of between 7 dB and 20 dB.
Because of this sensitivity, a flat frequency response in the 2 kHz to 6 kHz area, which is directly within the midrange crossover area, is not required. This sensitivity is illustrated in the Fletcher Munson curves as shown in FIGS. 1 and 2. If the curves of FIG. 1 are turned upside down, as in FIG. 2, they provide an indication of how the human hearing attenuates and accentuates parts of the audible frequency range.
Typical industry standard crossover designs do not take this human hearing sensitivity into consideration and, therefore, attempt to provide a flat response within this area. The subject invention, in contrast to the typical industry standard flat response design, provides a response that is inversely proportional to the increased sensitivity. This inversely proportional design will indicate a dip in response within the critical area when measured on a spectrum analyzer.